Chapter 2 - DrawSprocket
DrawSprocket is the part of Apple Game Sprockets that gives your Macintosh video game control over special display and device-access features. For some features, DrawSprocket interacts directly with the Mac OS; for others, it can make use of specialized video subsystems and third party video cards. Those features that are not directly supported in hardware are emulated in software in a highly optimized manner, allowing you to rely on their presence when creating your game.Before reading this chapter, you should be generally familiar with Apple Game Sprockets, as described in the preface to this book. This chapter does not discuss Macintosh graphics systems or drawing functions; for that information, please consult the appropriate reference, such as Inside Macintosh: Imaging With QuickDraw. This chapter does not discuss Macintosh video hardware; for that information, please consult Macintosh Family Hardware Reference and Designing PCI Cards and Drivers for the Macintosh Family.
DrawSprocket relies on the Display Manager for some of its tasks, and you can use Display Manager features in conjunction with DrawSprocket. See the Display Manager documentation for more information.
This chapter starts by introducing the features of DrawSprocket, and then shows how your game can use DrawSprocket to choose a resolution and pixel depth for drawing, allocate a display, perform gamma fading for smooth transitions, and use double-buffering or page-flipping to draw to the display. It also describes other features such as overlays, underlays, and pixel scaling. The section "DrawSprocket Reference" (page 2-22) provides a complete reference to the constants, data structures, and functions provided by DrawSprocket. For a list of constants, data structures, and functions see "Summary of DrawSprocket" (page 2-77).
Chapter Contents
- About DrawSprocket
- Display Configuration
- Contexts and the Play State
- Page Flipping and Software Buffering
- How Triple Buffering Works
- Gamma Fading
- Underlays, Overlays, and Transparency Masks
- Pixel Scaling
- Other Features
- Video Driver Support
- Using DrawSprocket
- Choosing a Context
- Initializing the Context Attributes Structure
- Finding a Context
- Reserving and Activating a Context
- Creating Underlays and Overlays
- How Underlays Work
- How Overlays Work
- Fading the Display
- Double-Buffered Drawing
- Improving Performance With Dirty Rectangles
- Cleaning Up Before Quitting DrawSprocket
- Debugging
- DrawSprocket Reference
- Constants
- Depth Masks
- Color Needs
- Special Display Features
- Buffer Kind
- Pixel Scaling
- Play State
- Data Structures
- Context Attributes Structure
- DrawSprocket Functions
- Using DrawSprocket
- Choosing a Context and Saving Preferences
- Manipulating a Context
- Drawing and Double Buffering
- Using Alternate Buffers
- Handling a Mouse
- Manipulating Color Lookup Tables
- Processing System Events
- Utility Functions
- Application-Defined Functions
- Summary of DrawSprocket
- Constants
- Depth Masks
- Color Needs
- Special Display Features
- Buffer Kind
- Pixel Scaling
- Play State
- Data Types
- Context Attributes Structure
- DrawSprocket Functions
- Using DrawSprocket
- Choosing a Context and Saving Preferences
- Manipulating a Context
- Drawing and Double Buffering
- Using Alternate Buffers
- Handling a Mouse
- Manipulating Color Lookup Tables
- Processing System Events
- Utility Functions
- Application-Defined Functions
- Result Codes
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